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AIX Down Under

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Anthony English is an independent contractor who solves expensive problems for businesses running IBM Power Systems.
He has written extensively about AIX and has been recognised for his contributions and thought leadership by being named an IBM Champion for Power Systems.

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A customer did a migration from AIX 5.3 to 6.1 and then called me to report a strange set of symptoms. Some file systems didn't mount following a reboot. When the file systems in the volume group (let's call it datavg) went to mount, they returned the error that there was no such device. If the customer ran an exportvg and an importvg, all the datavg file systems became available. But then another reboot was done and the datavg file systems didn't mount. Update: I have an idea of what might have happened. The customer (as I should have... [More]

One of the great strengths of AIX is
the Logical Volume Manager (LVM). It may not be completely foolproof,
but it does provide quite a lot of protection from administrator
errors. Here are a few common LVM tasks that
I've deliberately attempted to make a mess of. See how the LVM
reacts (Don't Try This at Home) Let's start with three Physical
Volumes. rootvg has one PV (booting from SAN) and datavg has two PVs. # lspv hdisk0
00c5a47ecf9edd3e rootvg active hdisk1
00c5a47ed021ea7d ... [More]

It's pretty easy to move a volume group from one AIX system to another. You unmount all the file systems from the source volume group, varyoff the VG, export the volume group ( exportvg ), and then remove the disks from the source system ( rmdev -dl hdisk N ). Then you assign the LUNs to the target host, import the volume group , mount the file systems, and check permissions. But what if you want to copy a volume group? You might want to replicate a volume group, by doing a flash copy across the SAN. Then on the remote site, you'd present the... [More]

An important warning about importing a VG I've been playing with LVM tunables, specifically to do with pbufs, to see if changes to the parameters stay with a volume group when it gets moved to a new LPAR. First, some background A pbuf is a pinned memory buffer. As this developerWorks article explains, "T he LVM always uses one pbuf for each individual I/O request, regardless of the amount of data that is transferred. AIX creates extra pbufs when adding a new PV to a VG." The lvmo command is used to manage pbuf tuning parameters. It... [More]

"Go live or go home" If you need to get a lot of data from one AIX host to another, there's
more than one way to do it quickly. During a migration to a new system, you may do a database dump or archive and want to get the data available to the new LPAR within a short time frame. You can tweak the network settings improve your SAN configuration (just turn on the turbo switch) and assign more resources to ease the bottlenecks. Of course there's Live Partition Mobility (LPM) and various High
Availability options but they may not be... [More]

Diamond in the SAN I recently
cloned an LPAR from a P6 to a less-busy P5 server via a mksysb
backup . Unfortunately, after starting up the new LPAR I found that there was an essential directory missing because it had been excluded via the /etc/exclude.rootvg file (-e option on mksysb). Let's call the directory /diamond (its name has been changed to protect the guilty who didn't back it up). I considered my options but each of them had a drawback. Option 1: restore directory contents from TSM Obstacle: unfortunately, the directory had... [More]